COLUMBUS -- Firefighters say part of a freight train that derailed and exploded in flames in Columbus was carrying ethanol.

Authorities say 10 or 11 cars derailed early Wednesday near Interstate 71, southeast of the Ohio State University campus. Assistant Chief David Whiting says three of those cars were tankers of ethanol.

Joel Priester watched the blast from his home two blocks away and said it "looked like the sun exploded."

Norfolk Southern said it wasn't immediately clear what caused the derailment. Authorities decided to let the fire burn out instead of trying to extinguish it.

A fire official says two people who ran toward the scene before the explosion were injured but were able to take themselves to a hospital.

The fire prompted the evacuation of a mile-wide area. By mid-morning Hazmat officials said it was safe to shrink the evacuation area.

The fire is being allowed to burn itself out. About twenty gallons of the liquid remain. Once the fire burns out, investigators can get into the site to assess the situation.